Paper
1 September 1998 New flatness measurement instrument for 230-mm lapped and polished photomasks
Paul G. Dewa, Andrew W. Kulawiec, Stephen K. Mack, John J. Nemechek
Author Affiliations +
Abstract
Tropel has developed a new instrument for the measurement of next generation photomasks. The instrument is capable of measuring the flatness of rough lapped, fine lapped and polished mask blanks with better than 0.1 micrometer accuracy. Well suited to production control and process development, the instrument utilizes a non-contact method to perform complete surface evaluation in less than 1 minute. The fundamental measurement technique is grazing-incidence interferometry. A novel optical design suppresses interference fringes from unwanted second surface reflections. This is a significant advantage over normal- incidence interferometers that typically require photomasks to be temporarily coated to address second surface interference effects. Coating and subsequent cleaning may damage polished photomasks as well as add unnecessary process steps.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Paul G. Dewa, Andrew W. Kulawiec, Stephen K. Mack, and John J. Nemechek "New flatness measurement instrument for 230-mm lapped and polished photomasks", Proc. SPIE 3412, Photomask and X-Ray Mask Technology V, (1 September 1998); https://doi.org/10.1117/12.328803
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KEYWORDS
Photomasks

Surface finishing

Polishing

Interferometers

Interferometry

Prisms

Reflection

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